A headspace solid-phase micro extraction (HS-SPME) and gas chromatography-tandem mass spectrometric (GC-MS/MS) method is described to detect hydrazine after derivatization with 1,1,1-trifluoro-2,4pentanedione (1,1,1-TFPD) to 3-methyl-5-(trifluoromethyl) pyrazole in industrial waste water. The following optimal HS-SPME conditions were used: 85 pm-carboxen-polydimethylsiloxane fibre, 100 mg L-1 TFPD, saturated NaCI, an extraction/derivatization temperature of 80 degrees C, a heating time of 40 min, and a pH of 9.5. Under the established conditions, the detection and quantification limits were 0.002 mu g L-1 and 0.007 mu g L-1 by using 5 mL of waste water and the intra- and inter-day relative standard deviations were less than 10.2% at concentrations of 0.02 and 0.1 pg L-1. The calibration curve showed good linearity, with r(2) = 0.998; the accuracy was in the range of 98.0-103%; and the precision of the assay was less than 10.2% in industrial waste water. Hydrazine was detected over a concentration range of 0.011-0.074 pg L-1 in 5 of 20 waste water samples. (C) 2016 Elsevier B.V. All rights reserved.